A null cipher is an unencrypted message crafted in such a way that the real message is "camouflaged" in a larger, innocent-sounding message. A null cipher is also sometimes referred to as an open code. Null ciphers have one big drawback: They do not always "sound" quite right. The message may read clumsily, and suspected messages can be detected by mail filters. Although innocent sounding, messages often go undetected and are allowed to flow through.
Following are some examples of messages containing null ciphers:
News Eight Weather: Tonight increasing snow. Unexpected precipitation smothers eastern towns. Be extremely cautious and use snowtires especially heading east. The highways are knowingly slippery. Highway evacuation is suspected. Police report emergency situations in downtown ending near Tuesday.
By taking the first letter in each word, the following message can be derived: Newt is upset because he thinks he is President.
Fishing freshwater bends and saltwater coasts rewards anyone feeling stressed. Resourceful anglers usually find masterful leapers fun and admit swordfish rank and overwhelming any day.
Taking the third letter in every word, the following message emerges: Send lawyers guns and money.